Lens-grinding apparatus



Apr 22, 1924.v

G. s. DEY

LENS GRINDING APPARATUS Filed May 31. 1921 INVENTOR GILBERT S.DEY

BY 1, mum- H WM ATTORNEY Patented Apr. 22, 1924.

GILBERT S. DEY, OF SOUTHBRIDGE, MASSACHUSETTS, ASSIGNOR T0 AMERICANOPTI- OF MASSACHUSETTS.

LENS-GRINDING- APPARATUS.

Application filed May 31, 1921.

T 0 all whom it may concern.

Be it known that I, GILBERT S. Day, a citizen of the United States,residing at Southbridge, in the county of Worcester and State ofMassachusetts, have invented certain new and useful Improvements inLens- Grinding Apparatus, of which the following is a specification.

This invention relates to improvements in lens-grinding apparatus andhas particular reference to an improved type of tool for use in thesurfacing of lenses.

One of the principal objects of the present invention is the provisionof a novel and improved construction of tool especially adapted for usein the formation of multifocal lenses.-

A further object of the present invention is the provision of animproved tool which shall have a sharp outer edge or bounding line sothat it can be worked up to an exact point without causing aberration atthe particular point in question and which will satisfactorily conformto and properly abrade or polish the entire surface covered by the tool.

A further object of my invention is the provision of an improved form oftool and process of producing the tool so that the lubricating fluidemployed in the grinding or polishing operation will properly work underand to the center of the tool and prevent overheating of the parts orinjury to the work.

Other objects and advantages of my improvement should be readilyapparent by reference to the following specification taken in connectionwith the accompanying drawings, and it will be understood that I maymake any modifications in the specific features of constructiondisclosed within the scopeof the appended claims without departing fromor exceeding the spirit of my invention.

Figure I represents a plan view of an apparatus making use of myimprovement.

Figure II represents a sectional view as on the line IIII of Figure I.

Figure III represents an enlarged detailed section through the toolproper.

Figure IV represents a bottom view of the tool'shown in Figure III.

Figure V represents a bottom plan view of a slightly different form oftool.

Serial No. 473,784.

Figure VI illustrates the mation of and Figure VII represents asectional view through another modified form of my tool.

In the drawings, the numeral 1 designates the main frame or base of alens-grinding machine having rotatably mounted therein the spindle 2 ofthe lens holder 3 adapted to hold the lens blank at for rotary movement.Carried by the frame may be a' suitable bracket or support 5 for the arm6 carrying the upper spindle 7 rotatable as by power suitably applied tothe pulley Sand bearing my improved grinding tool which may be eitherloosely mounted for driving movement on the end of the spindle or may bepositively driven by the spindle as preferred.

My improved tool, in the form illustrated in Figures III and IV,comprises the base portion9 having the socket 10 to receive the spindle7 and having suitably formed or secured thereon the outer annulargrinding member 11 which may be formed from fibre, hard pitch, or otherrelatively stiff and un yielding polishingmaterial. This member 11 is inthe form of a wall, preferably in the shape of a truncated cone, andencloses the central polishing material 12 which fills process of forthetool illustrated in Figure V,

the entire interior of the member 11. This latter may be either a softpitch composition as shown in Figure III or may be of felt or of cheesecloth, scrim. or other suitably reticulated material. Figure V shows abottom plan view of a polisher having the effect of the use ofreticulated material but in which the soft pitch center or the like isemployed.

The process of-formation of this particular tool is illustrated inFigure VI in which it will be seen that there is a base mold section 13into which fits the base block 9 and annular portion 11 which havepreferably first been formed in another suitable mold. The parts havingbeen put in this position, the center of the member 11. is then filledwith the polishing material 12 and the plunger 14 brought down againstsaid material. Said member 14 has its lower face formed to the curvewhich it is desired to reproduce on the face of the tool and ispreferably heated. It is also provided with the wire screen or meshportion 15 held as by the lateral fastening members 16, the-heat actingon these to have them insufficiently warm condition to soften thematerials 11 and 12. Therefore, as the plunger" is brought down it willpress the parts 11 and 12 to conform to the shape of thealower face ofthe plunger forming in the member 11 the groovesi17 which receive thesecuring member 16 and forming on the central softened portion thereticulated surface 18.

A tool of this type when properly formed may be used for polishing withextremely satisfactory results in that as the fluid is applied to thesurface of the lens and'the tool and lens rotated in the usual manner,the lubricating fluid will work under the hard plunger 11 andparticularlyin through the passages formed by the groove IT and willspread to the center of the tool to keep it properly lubricated asthrough the grooves or passages formed by the reticulation of thesurface.

This structure is particularly desirable since in the polishing oflenses with a solid polisher care has always had to be observed that thecenter of the tool was kept properly lubricated as it otherwise has atendency, particularly in the case of a pitch polisher or the like, tobecome dry when it will heat and be pulled somewhat out of shape throughthe friction with the lens destroying the efliciency of the polisher.This is particularly noticeable when a slight projection or the like isformed on the polisher which will glaze over and then delay thepolishing actilgn, cause burned effects on the glass or the li e.

It will be noted that my improved polisher is especially adapted for useon bifocal lenses in which it is desired to polish the lens exactly upto a given line which may be either a cliff or ridge or a merged line ofjoinder between the surfaces. In any event, it is essential that thepolisher be sufiiciently stifi and rigid to hold its form exactly up tothe edge to form a sharp line and without rubbing over the edge causingaberrations. At the same time it is desirable that the tool be centrallyproperly lubricated to ensure proper polishing action and that it be ofsuch shape that it will have a tendency to conform to the shape of thelens to be polished during the polishing operation and ordinarilywithout materially altering the shape or curve which has already beengenerated. on this surface. A continuous hard polisher cannot be assatisfactorily employed for these purposes due to its tendency tomaintain its own shape rather than to conform to the lens, while a softpolisher is deficient in that it will not preserve the necessary sharpdividing line. I have found, however, that by my improved combinationextremely satisfactory results can be obtained, the thickness of themember 11 being such that it will hold the edge, will satismensesfactorily polish out the edge but will wear down substantially equallywith the central portion so that the entire tool is at all times inproper polishing engagement with the glass, its outer edge is positivelymaintained, there is produced a satisfactory and correct line ofdivision between the fields of the lens, the center portion being softenough to conform somewhat to the shape of the lens, and there issecured the necessary rapid polishingaction to produce quickly thedesired lens. 7 7

It will he understood that while I consider as most desirable thecombination of hard and soft pitches or the like the form shown inFigure V, various modifications may be made and I may, if desired,obtain the same reticulated effect or the like by the use of a suitablefabric material disposed in layers as at 19 in the interior of the wall11 as specifically illustrated in Figure VII.

I would also call particular attention to the truncated cone shape of myimproved tool. This has a particular advantage in that with this shapeof outer wall it is possible to work up exactly to the edge or cliff ofthe lens and to polish properly the surface without any liability of thetools first striking the overhang or upper edge of the clilf or anyliability of the tools coming into contact with and pitching this edgewhile allowing the free sidewise movement up toward the edge. In thisway I am able in connection with a depressed bifocal to polish perfectlythe entire surface without interfering with the edge or line of joinderwhich may be left gray and unpolished if desired or may be speciallypolished. Also, this cone effect makes it easier as the tool wears downto maintain a sharp edge rather than to have a rounding over edge as ismore likely to occur with right angle corner.

I claim: 1

1. A lens polishing tool. of the character described, comprising anouter surface formed from a. hard pitch composition, said surface beingin the form of an annular wall, and a softer polishing material enclosedwithin said wall.

2. A lens polishing tool of the character described. comprising an outerannular wall formed from relatively hard composition, and an enclosedportion formed from a soft pitch composition.

3. A lens grinding member comprising an outer enclosing wall formed froma hard pitch composition material, and an inner portion formed from softpitch composition material, the outer hard pitch member having aplurality of grooves at its operative surface communicating with saidinner soft pitch composition material.

4;. A lens polishing tool of the character described, comprising arelatively hard frustro-conical outer surface formed from a hard pitchcomposition material, and a soft pitch composition material enclosedwithin said outer surface, the lower faces of said hard and soft pitchcomposition materials being of arcuate configuration.

5. A lens polishing member of the character described, comprising anouter relatively hard composition enclosing wall formed from a hardpitch composition material, and an inner reticulated polishing portionformed from a soft pitch composition material.

6. A lens polishing tool of the character described, comprising arelatively hard composition outer surface formed from a hard pitchcomposition material and having a frustro-conical shape, said surfacebeing in the form of an annular wall and an inner portion of softermaterial formed from a soft pitch composition material, said outermember having a plurality of grooves at its operative surfacecommunicating with said inner softer material, the operative surfaces ofsaid inner and outer portions being of arcuate configuration, andcriss-cross grooves formed on the opposite surface of said innerportion.

In testimony whereof I have aflixed my signature, in presence of twowitnesses.

GILBERT S. DEY.

Witnesses:

Susan OASAZZA, ALICE G. HASKELL.

